The Duchess of Cambridge's pregnancy sickness will almost certainly rule her out of attending the UK premiere of The Hobbit, after a reoccurring bout of a severe form of morning sickness saw engagements cancelled over the weekend.

One Sunday, Prince William pulled out of attending the British Military Tournament to spend time with his pregnant wife as she recuperates after leaving hospital where she was treated for hyperemesis gravidarum.

He told charity boss Michael O’Higgins: “It’s a long old process but she is getting there. She feels like it is going to go on for ever.”

Kate and William are guests of honour at Wednesday's screening of the latest blockbuster from director Peter Jackson, who created the popular Lord of the Rings movie trilogy.

St James's Palace said a decision on whether Kate would join the movie audience at the Odeon, Leicester Square would be made nearer the time,

A spokeswoman for Pregnancy Sickness Support, a charity which helps women with Kate's condition known as hyperemesis gravidarum, said the Duchess would be experiencing constant nausea with regular vomiting.

Caitlin Dean, who suffered from the same illness during three pregnancies and is a trustee of the charity, said: "I would be amazed if she's able to go to the premiere. When she's more like 14-plus weeks possibly she will have days when she can do that."

Mrs Dean added: "The sickness is constant and ongoing, it's just a matter of keeping on top of it.
"She might have days that are a bit better than other days but realistically you don't have days when you're actually well."